A 45-year-old man with frequent bleeding in the nose came to a referral hospital. The internist requested PT, INR and APTT to the laboratory. The laboratory technologist collected blood with citrate test tube and ran PT and INR tests. Before performing APTT, the technologist added kaolin suspension to the APTT reagent. What is the effect of kaolin in the APTT test? a. Activator b. Anticoagulant c. Inhibitor d. Decelerator
